Process of detinning tin-plate by means of chlorin.



I No Drawing.

.unirnn srarns PATENT OFFICE. 7

HANS VON soiin'rz, or WETZLAR, GERMANY.

PROCE$S F DETINNING TIN-PLATE BY MEANS OF CHLOE/IN.

To all whom it may concern:

Be it known that I, HANS VON SoHi'iTz, merchantand metallurgist, citizenof Ger- 'many, subject of the King of Prussia and Emperor of Germany,residing at Philosophenweg 3, Wetzlar, in the Kingdom of Prussia andEmpire of Germany, have invented certain new and useful Improvements in.Processes for Detinning Tin-Plate by Means of -Chlorin, of which thefollowing is a full, clear, and exact description.

The treatment of tin plate material (tin plate waste and the like) withchlorin serves a double purpose, namely the obtaining of iron as free aspossible from tin for the purpose of smelting, and a yield of tin, thelatter in the form of thepurest possible anhy drous stannic ohlorid. I

In the application of the process as known, it has nothitherto beenpossible to avoid grave defects which arose mainly' owing to thefactthat the moisture adhering more or less,.and also im arted by theatmospheric air, to the material to be detinned, caused the formation ofsolid, e; e; hydrated stannic chlorid. The result of this is that in theapparatus crusts of basic tin tetrachlorid are eposited which attack theiron or cause the formation of ferric chloridwhich then enters as animpurity into'the cliloritic tin and derange various pumping andventilator mechanisms used in the process of chlorination, causing anabnormal increase in the power consumption of this machinery and indeedbringing the machines to a standstill after a short time of ,'workingand in addition narrowingo'r choking upthe pipes. It is clear in shortthat this epresents a source of constant derangement in working-and alsothe cause of large wear and tear. Finally the stannic'chlorid crustsdeposited in the apparatus are not utilizable for the mar ket, andtherefore represent a permanent loss of product. A series of furtherdefects is inherent in the use of high chlorination pressure. Thepressure required for forcing I gfect yield of liquid stannic chlorid.This is the case in a higher degree in proportion as the raw material ismore powerfully compressed. The more powerful the compres- Specificationof Letters Patent. Patented NOV. 23, 1909. Application filed November 4,19 08. Serial No. 4;61,081.

sion the higher the pressure of the chlorin must be, and with the moredesnity will the fluid be retained inside the material.

Finally the tin plate cuttings, if after de-tinning they are subjectedto special washing,

so greedily absorb the Washing liquid'andretain it with such energy thatrailway;

trucks loaded with v washed bundles show;

considerable'leaka'ge after runningfor 'ours..

By this meansf-notjonly' is the rusting f th'e de-tinnedcuttings-precisely the f i thing which it is desi'r'ableto avoid as far aspo'ssiblepron ot'ed,, but; injury; is done' to, the trucks and; otheritieansjusetl'; for transport by corrosion ofthe-mon'p'arts; decay oftheAll these defectsareinten v by the present and, its methods application.I y

The inventive ideafisj lb sedifin ,the,

place on the avoidance oft enseofiall-zinei chanical devices 1nthecour'se';ofathechlori-i ed -to be avoided.

nation process. Further, thei'-aw material to be de-tinned is first of,alb'co'inpletely dried before being chlorinedi 7 ill liejchlori wnation process itself'is caifriedfOnt, notbyforcing the chlorin into thesubstance under excessive pressure butby suctionga'vacuuni havin beencarefully produced? beforehand v c n in the raw material.

' The present process is first of all charac terized by the fact thatthe tin plate ma-fl terial placed in a closed chamber is deprived of allmoisture, and'is, before and during "chlorination, 'cooledby the naturalcooling action of gases expanding from the condensed or liquefied state;

After the removal of moisture and pref liminary cooling of the material,the strongest possible vacuum .18 produced in the chlorination chamber.The chlorin is then vaporized from the liquid state, cold being thusdeveloped, and is mixed in .the gaseous state with cold air-which maylikewise expand from the liquid state andis let into the chlorinationchamber, all pressure being avoided as far as possible. The chloriirandthe air may suitably be introduced into the vacuum chamber throughseveral nozzles distributed uniformly over the material in such a waythat the mixture iimuedialoly and uniformly distributed over the 'cntirccontents of the receptacle or chamber. The action. of the chlorin on thetin therefore llU takes place quite uni ormly everywhere i tetrachloridstill adhering to the (l6- fi6(l which results in a like uniformdistribution of the heat of combustion. The growing heat of combustionis again counteracted by the coldness of the automatically circulatinggas mixture. In proportion as the tin absorbs the chlorin there is anautomatic further indraft of chlorin and air, the coldness of whichcontinually cools the gradually warming mass. ln this operation the massof tin plate itself has a moderating -e.tl'ect.

The chlorination is ctmtplete if the entering gases havefinallydestroyed the vacuum in the chlorination chamber and a condition ofequilibrium has set in. It must however be observed that'during theentire process no noticeable increase of pressure above the atmosphericoccurs.

The gases passing through the material carry with them the liquidstannic chlorid in Iormation and in this Way etfectively assist itsliberation. The avoidance of high pressure in admitting the chlorin isfurther aimed at obviating any excess of chlorin in the stannicchloritl, wliichwoulcl be highly detrimental to the later use of thisproduct.

The stannic chlorid formed is itself drawn oil from time to time in asuitable way.

Only after completion of the entire chlorination process is there ashort contact of the chlorin with mechanical devices, the last residuesof it being sucked out of the chlorination chamber by means of a pumpand conveyed into a second chamber, where these chlorin residues aredeposited in some suitable way, for instance in water.

A gentle raising of the de-tinned material to a dull glow by heatingfinally effects its rapid and complete liberation from the very lastchemical residues, and at the same time results in the coating of thede-tinned stuff with an oxid-layer serving .as a rust protector.

As receptacles in which to carry out the chlorination, chambers in thestyle of coke furnaces are contemplated, in which the -ma*-" terial tobe detmned is placed in bundles,

or better still, in a block filling up the entire chamber. In using suchblocks the final work will consist in cutting them into suitable piccesimmediately after heatihg. The

adoption of these large blockshas' for itsobject to give the material auniformly solid form without any spaces, by means of a sing]; mechanicaloperation, thus allowing of rapid charge and uniform chlorinationwithout special intermediate receptacles being required.

The process thus described may then be subjected to two furthermodifications one of which consists in the special method of drying thetin plate-goods prior to subjecting them. to the chlorin process and thesecond improvement deals with the removal of the last remnants of thetin sullioiently prepared and effectively dried;

after this the de-tinning takes place in the way before described,whereupon now, for the purpose of completely removing the last residuesof the tin tetrachlorid still adhering to the de-tinned plate, thelatter is subjected to a special washing process in the chlorinationchamber itself. This washing process is carried out in the chlorinationchamber by submerging the de-ti'nned material in water once or more, orby treating the tin plate bundles for a certain length of time by meansof a current or" water flowing through. A further advantage in thisWashin process to be carried out in the chlorination chamber lies in thefact that the latter chamber is itself cleaned by the washing process.Again in the same chlorination chamber there finally takes place thedrying of the de-tinned and Washed material inas- -much as the chamberis subjected to direct or indirect heating, or hot air, waste gases,

process proper and the like, are forced through the washed materialsimilarly as in the above described preliminary drying process. Anotherad-. vantage of the subsequent drying of the detinned and washedmaterial in the chlorin vchamber itself, consists therein that by thismeans the chamber is itself also dried and is ready for charging againimmediately after emptying. After washing and drying the furthertreatment of the completely de-tinned plate takes place, whereby theseplates are compressed into the large blocks described.

What I claim is:

1. The process which consists in subjecting tin-bearing material to theaction of chlorin gas, the gas being below normal temperatures.

2. The process which consists in placing the tin-bearing material in aclosed chamber, producing a vacuum therein and allowin chlorin as toexpand from the condense or liqu'e ed state into such chamber.

3. The process which consists in completely drying tin-bearing materialand then subjecting it to the action of chlorin gas, the gas being belownormal temperatures.

he process which consists in subjectin'g tin-bearing material to theact-ion of chlorin cooled below normal temperature to remove the tin,and then heating the tin material.

5. The process which consists in placing tin-bearing material in aclosed chamber,

subjecting the material in said chamber to heat to dry the same, andthen subjecting the material in said chamber to the action of chlorirrcooled below normal temperature.

6. The process-which consists in placing tin-bearing material in aclosed chamber, subjecting the material in said chamber to heat to drythe same, then subjecting the material in.- said chamber to the actionof chlorin cooledbelownormal temperature, and removing the tintetrachlorid from said chalmben.

7 The process which consists in placing tm-bearing materlal 1n a closedchamber,

subjecting the material in said chamber to heat to dry the'same, thensubjecting the material in said.- chamber to the action of chlorincooled below normal temperature, then washing the material to removethe'tin tetrachlorid, and subsequently drying the same.

8. The process of treating tin-bearing material which consists inwashing, drying and cooling such material and then subjecting it ina'closed chamber to the action of chlorin gas cooled below normaltemperature.

9. The process which consists in placing a tin-bearing material in aclosed chamber, producing a vacuum therein,.and allowing chlorin gas toexpand into such chamber.

In witness whereof, I subscribe my signature, in presence of twowitnesses.

HANS VON SOHT ITTZ.

Witnesses JEAN GRUND, CARL GRUND'.

